P0400-f8 fault code

[leeeager]

Hi guys have a vectra 04 2.0dti that has brought up this fault code. Have cleaned the egr valve and checked all vacum pipes as other threads suggest. Any other checks I should do before I buy an egr valve.
Thanks Lee

[Graham]

What about your boost pipes, the big black ones. prone to splitting .

[leeeager]

Have checked all pipe work including turbo to intercooler and boost pipes. When the fault isnt there it drives great

[Graham]

Do you loose power when this fault occurs?
If so then its a good chance you do have a split in the boost pipes or vacuum pipes. It only needs to be a small split, as when you are putting the engine under load more boost is required, therefore forcing its way out the tiny split.

You may have to take your boost pipes off, and bend them around to find the split.

[Signum-Steve]

When checking the boost pipe/inter-cooler pipe work get someone to rev the engine while you take a look. You will see the pipe work expand. It will give you a good chance to feel for or see/hear the splits if there are any present. When checking the vacuum pipe work pay particular attention to the rubber elbows and joints. these perish and split/crack. The one that fits onto the turbo actuator takes a lot of heat so can become very brittle.

[leeeager]

Cleaned egr valve yesterday and checked all pipework. Went like a pig everytime I tried it. Took it to work today and no issue then give it a good test on way home seems to be better than before. Fingers crossed will keep you posted. Gonna clean inlet manifold and boost sensor when I get a chance along with full service.

[bobssignum]

Have you insured the cable to the egr is connected properly , or is not stretch .
another member on here recently had a problem of p0400 fault code coming up even though he had just fitted a new egr , it turned out that he had twisted the wire feed and caused it to be under tension.
under advisement he reseated cable and fault dissapeared
just a thought , but worth a try